The present invention relates to an X-ray CT apparatus which applies a cone X-ray beam spread in fan form with a thickness and detects the X-ray beam by X-ray detectors two-dimensionally arranged in a plane approximately orthogonal to the direction of its application.
Each of X-ray detectors employed in an X-ray CT apparatus has recently been advanced in multichanneling thereof in a scan direction and multirowing thereof in a thickness direction with advances in solid-state X-ray detectors. For instance, each of X-ray detectors in a channel direction results in one having about 1000 channels, whereas each of X-ray detectors in a thickness direction results in one having about several tens of rows (refer to a patent document 1, for example).
Under such circumstances, the X-ray CT apparatus needs a large number of electronic circuit portions at a data acquisition section which amplifies and processes an electric signal detected by the corresponding X-ray detector. The X-ray CT apparatus incorporates these electronic circuit portions in a rotational section lying in a gantry and is rotated together with an X-ray tube and the X-ray detectors to collect or acquire data. Thus, the data acquisition section may preferably be compact. Providing the electronic circuit portions corresponding to all the X-ray detectors in a one-to-one relationship is not easy in terms of the efficiency of accommodation thereof into the rotational section, the cost thereof, etc.
Therefore, a plurality of X-ray detectors, e.g., two channels in a channel direction are electrically connected to each other to function as one channel. They have been connected to the electronic circuit portions of the data acquisition section. Thus, the electronic circuit portions smaller in number than the X-ray detectors are capable of performing imaging using the X-ray CT apparatus.
[Patent Document 1] Japanese Unexamined Patent Publication No. 2003-144429 (Page 6 and FIG. 3)
According to the background art, however, the resolution of an imaged X-ray CT image is degraded and the X-ray detectors existing in large numbers are not effectively utilized. That is, the resolution of the X-ray CT apparatus is degraded as the size of each X-ray detector in the channel and thickness directions increases. Therefore, the resolution is degraded by electrically connecting a plurality of channels and configuring the same as a large X-ray detector equivalently.
Since the small X-ray detectors exist in large numbers, the X-ray CT apparatus is capable of originally performing imaging in high resolution. However, this imaging in the high resolution is restricted by electrically connecting the two channels in the channel direction.
In particular, the multichanneling and multirowing of the X-ray detectors are carried out with relative ease with the advances in the solid-state X-ray detectors. On the other hand, it is not easy to increase the electronic circuit portions of the data acquisition section in terms of the above-described efficiency of accommodation and cost.
It is important from these points to consider how an X-ray CT apparatus that performs a plurality of pieces of imaging small in resolution degradation too simultaneously while suppressing an expansion of the data acquisition section that receives the electric signal of the X-ray detector, would be realized.